This invention relates to wheel end assembly, and more particularly to a wheel end assembly for an inverted portal axle as used in a mass transit vehicle.
Mass transit vehicles, such as trolley cars, buses, and the like typically have seats aligned at the lateral sides of the vehicle, with a central aisle and floor extending along the vehicle. In order to facilitate entering and exiting from the vehicle, it is desirable to have the vehicle floor and aisle positioned relatively low to the ground. This provides faster cycle time during stops and facilitates boarding for all passengers, especially for elderly and disabled passengers as well as for children.
Mass transit vehicles typically have several axles that support, drive and steer the vehicle. Many such vehicles provide a rigid axle having an input positioned off-center near one wheel end to form an inverted portal axle configuration. The input to the portal axle rotates about a longitudinal axis and is typically low to the ground to allow the vehicle floor to be as low as possible. The output to the wheels defines a lateral axis that is vertically higher than the longitudinal axis for the input.
This inverted portal axle includes a short axle shaft member that drives the wheel end near the input and a long axle shaft member that drives the opposite wheel end. The portal axle further includes a pair of gear assemblies, one gear assembly positioned at each wheel end, to raise driving input from each of the axle shafts up to the vertically higher output position at the wheels. Typically this gear assembly includes a gear housing, an input gear driven by the respective axle shaft, an output gear for driving the wheel, and a pair of idler gears in meshing engagement with the input and output gears.
The output gear drives a wheel shaft that is enclosed within a spindle that is mounted to the gear housing. A wheel hub is mounted for rotation relative to the spindle and receives driving input from the wheel shaft. A brake spider is also mounted to the gear housing to support a brake input member. This traditional configuration incorporates at least three bolted joints and four bearings to support the rotating components. Assembly time and overall component cost is significant due to the large number of components and complexity of this configuration.
Accordingly, it is desirable to provide a simplified wheel end assembly for a portal axle configuration to reduce cost and assembly time in addition to overcoming the other deficiencies in the prior art discussed above.